1. Field of the Invention
The present invention relates to a ferromagnetic tunnel magnetoresistive element and a magnetic head using the same.
2. Description of Related Prior Art
Conventionally, ferromagnetic tunnel magnetoresistive (TMR) elements have been proposed as one type of magnetoresistive elements. JP-A-10-4227 describes a magnetic head using a TMR element. However, the magnetoresistance of such a conventional TMR element depends greatly on an applied voltage where a TMR ratio becomes lower as a voltage is applied. In order to employ the TMR element in a magnetic head or a magnetic memory, it is necessary to increase the output while decreasing the dependency thereof on the applied voltage. An increase in the output can be achieved by applying a half-metallic ferromagnet whose degree of spin-polarization is higher than that of a magnetic ferromagnet used in the conventional TMR element. An attempt to increase a TMR ratio in a TMR element using a material associated with a high degree of spin-polarization (La0.7Sr0.3MnO3/SrTiO3/La0.7Sr0.3MnO3) is described in Europhysics Letters, 39(5), pp. 545–549 (1997). Physical Review Letters describes that 40% to 50% TMR ratio can be obtained up to an applied voltage of about 1 V in Co/SrTiO3/La0.7Sr0.3MnO3.